Cockney Rhyming slang (Cockney=Amusing London Dialect, for all you thick arse americans...That's LONDON...ENGLAND...understand?). Commonly accepted to mean a person of the jewish faith. Derivation follows from 'four wheel skid' = 'Yid' = Yiddisher' = person of the jewish faith. Also called 'four wheeler'.
Presumably in the modern age it is only a matter of time before they are called 4x4 incidents!
"Did you know that Heimi over there was a four wheel skid?"
"No, I knew he was a tight bastard, but I just thought he came from Bedford"